Plants or plant materials contain both volatile and non-volatile components, which collectively dictate unique odor and/or flavor profiles. Volatile components, such as essential oils, provide a plant or plant material with a distinctive odor, while non-volatile components, such as resins, provide a plant or plant material with a distinctive flavor or taste. Plants or plant materials also contain non-volatile components, which are inert (e.g., cellulose, lignin, ash). Such components are commonly referred to as “impurities”.
Non-volatile components from certain plants or plant materials (e.g., medicinal plants) may influence or cause certain physiological effects and, in some instances, may provide certain health benefits. Such components, which include alkaloids, antioxidants and steroids, are commonly referred to as “active principals”.
An essential oil is a volatile mixture of esters, aldehydes, alcohols, ketones and terpenes, which can be prepared from plants and plant parts. Examples of essential oils include oil of cinnamon, prepared from the dried bark of the roots of Cinnamomum zeyloriaceae, cajeput oil, eucalyptus oil, prepared from the fresh leaves and branches of various species of Eucalyptus, and fennel oil, prepared from dried ripe fruit of Foeniculum vulgare. 
Essential oils are mainly responsible for the unique or characteristic aroma of a plant or plant material, and are typically prepared by subjecting the plant or plant material to a distillation process. A number of different distillation procedures are known. One such procedure involves injecting/distilling a plant bed with steam, condensing the steam and separating the oil phase from the aqueous phase to obtain the essential oil.
Oleoresins are mixtures of essential oils and resins and are described as representing the complete flavor profile of plants or plant materials. It is noted that the resinous or non-volatile component of oleoresins provides these materials with added stability when subjected to heat during food processing. This feature is recognized as a major advantage over essential oils.
Current oleoresin extraction technology involves extraction with one or more solvents followed by removal of the solvent(s) by evaporation. One such procedure involves soaking plants or plant materials in one or more solvents (e.g., a mixture of ethanol and water for extraction of vanilla, hexane for extraction of numerous varieties of spices) and removing sufficient quantities of the solvent(s) from the resulting extract. For example, approximately 35% ethanol in vanilla extracts, and less than 25 parts per million (ppm) hexane in spice extracts are considered acceptable solvent levels.
The volatile and non-volatile components, including essential oils and oleoresins, which are extracted from plants or plant materials tend to have different aroma and flavor characteristics from those of the natural plant. The diminished quality of these extracted materials is due, in part, to thermal degradation of the components, which occurs during extraction, and to the presence of impurities (e.g., lignin), which remain in the plant extract.
A need exists for an extraction process, which addresses the problems of thermal degradation and the presence of impurities in resulting plant extracts.
It is therefore an object of the present invention to provide such a process.
It is a more particular object of the present invention to provide a low temperature process for extracting volatile and non-volatile components (i.e., principal components) from plants or plant materials.
It is yet a more particular object to provide a process, which improves the yield and quality of principal components extracted from plants or plant materials.
It is a further object to provide a high quality plant extract, which retains the active principals, and the natural aroma, color, and flavor of the plant, or plant material from which it was obtained.